/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.barcode.core;

import java.util.Hashtable;
import java.util.Map;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.DecodeHintType;
import com.google.zxing.FormatException;
import com.google.zxing.NotFoundException;
import com.google.zxing.Reader;
import com.google.zxing.Result;
import com.google.zxing.ResultMetadataType;
import com.google.zxing.ResultPoint;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.DecoderResult;
import com.google.zxing.common.DetectorResult;
import com.google.zxing.qrcode.decoder.Decoder;
import com.google.zxing.qrcode.detector.Detector;

/**
 * This implementation can detect and decode QR Codes in an image.
 *
 * @author Sean Owen
 */
public class QRCodeReader implements Reader
{
    private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
    private final Decoder decoder = new Decoder();

    protected Decoder getDecoder()
    {
        return decoder;
    }

    /**
     * Locates and decodes a QR code in an image.
     *
     * @return a String representing the content encoded by the QR code
     * @throws NotFoundException if a QR code cannot be found
     * @throws FormatException if a QR code cannot be decoded
     * @throws ChecksumException if error correction fails
     */
    public Result decode(BinaryBitmap image , Hashtable hints) throws NotFoundException, ChecksumException, FormatException
    {
        DecoderResult decoderResult;
        ResultPoint[] points;
        if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE))
        {
            BitMatrix bits = extractPureBits(image.getBlackMatrix());
            decoderResult = decoder.decode(bits, hints);
            points = NO_POINTS;
        }
        else
        {
            DetectorResult detectorResult = new Detector(image.getBlackMatrix()).detect(hints);
            decoderResult = decoder.decode(detectorResult.getBits(), hints);
            points = detectorResult.getPoints();
        }
        Result result = new Result(decoderResult.getText(), decoderResult.getRawBytes(), points, BarcodeFormat.QR_CODE);
        if (decoderResult.getByteSegments() != null)
        {
            result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.getByteSegments());
        }
        if (decoderResult.getECLevel() != null)
        {
            result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, decoderResult.getECLevel().toString());
        }
        return result;
    }

    @Override
    public void reset()
    {
        // do nothing
    }

    /**
     * This method detects a barcode in a "pure" image -- that is, pure monochrome image
     * which contains only an unrotated, unskewed, image of a barcode, with some white border
     * around it. This is a specialized method that works exceptionally fast in this special
     * case.
     */
    public static BitMatrix extractPureBits(BitMatrix image) throws NotFoundException
    {
        int height = image.getHeight();
        int width = image.getWidth();
        int minDimension = Math.min(height, width);
        // And then keep tracking across the top-left black module to determine module size
        //int moduleEnd = borderWidth;
        int[] leftTopBlack = image.getTopLeftOnBit();
        if (leftTopBlack == null)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        int x = leftTopBlack[0];
        int y = leftTopBlack[1];
        while (x < minDimension && y < minDimension && image.get(x, y))
        {
            x++;
            y++;
        }
        if (x == minDimension || y == minDimension)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        int moduleSize = x - leftTopBlack[0];
        if (moduleSize == 0)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        // And now find where the rightmost black module on the first row ends
        int rowEndOfSymbol = width - 1;
        while (rowEndOfSymbol > x && !image.get(rowEndOfSymbol, y))
        {
            rowEndOfSymbol--;
        }
        if (rowEndOfSymbol <= x)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        rowEndOfSymbol++;
        // Make sure width of barcode is a multiple of module size
        if ((rowEndOfSymbol - x) % moduleSize != 0)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        int dimension = 1 + ((rowEndOfSymbol - x) / moduleSize);
        // Push in the "border" by half the module width so that we start
        // sampling in the middle of the module. Just in case the image is a
        // little off, this will help recover. Need to back up at least 1.
        int backOffAmount = moduleSize == 1 ? 1 : moduleSize >> 1;
        x -= backOffAmount;
        y -= backOffAmount;
        if ((x + (dimension - 1) * moduleSize) >= width || (y + (dimension - 1) * moduleSize) >= height)
        {
            throw NotFoundException.getNotFoundInstance();
        }
        // Now just read off the bits
        BitMatrix bits = new BitMatrix(dimension);
        for (int i = 0; i < dimension; i++)
        {
            int iOffset = y + i * moduleSize;
            for (int j = 0; j < dimension; j++)
            {
                if (image.get(x + j * moduleSize, iOffset))
                {
                    bits.set(j, i);
                }
            }
        }
        return bits;
    }

    @Override
    public Result decode(BinaryBitmap arg0 , Map<DecodeHintType, ?> arg1) throws NotFoundException, ChecksumException, FormatException
    {
        return null;
    }

    @Override
    public Result decode(BinaryBitmap arg0) throws NotFoundException, ChecksumException, FormatException
    {
        return null;
    }
}
